XML (=extensible markup language) is a language, which allows a structured description of the content of a document by way of XML schema language definitions. A more detailed description of the XML schema and the structures, data types and content models used therein can be found in the references
http://www.w3.org/TR/2001/REC-xmlschema-0-20010502/,
http://www.w3.org/TR/2001/REC-xmlschema-1-20010502/,
http://www.w3.org/TR/2001/REC-xmlschema-2-20010502/.
Methods, devices or systems for coding and decoding XML-based documents are known from documents relating to the MPEG-7 standard, in particular ISO/IEC 15938-1 “Multimedia Content Description Interface—Part 1: Systems”, Geneva 2002.
Extensions to the method, devices or systems for coding and decoding XML-based documents are known from documents relating to the MPEG-7 standard, from the German application with the official reference 10351897.5. This discloses a method for coding a structured document, in particular an XML-based document, with which a plurality of codes are generated by means of one or more schemas and/or name spaces, with respectively separate codes, which are independent of other schemas and/or name spaces, for the elements defined and/or declared in the schemas and/or name spaces and/or in the groups of schemas and/or name spaces, being allocated for a schema and/or name space and/or a group of schemas and/or name spaces.
These allow efficient coding, even where schemas are not known in full to the encoder and/or decoder. This is achieved in that code tables are separated based on name spaces for the data types, global elements and replacement groups, with a name space referring to a space, in which names of data types (type names) used therein are allocated unique meanings and defined therewith.
Known methods for the binary representation of MPEG-7 and other XML-based descriptions or documents have shortcomings in respect of encoding and decoding complexity, in so far as the XML description or XML document to be coded is based on a number of name spaces. For example, in the documents cited above a method is defined for the binary representation of XML descriptions and XML documents based on schemas and name spaces. (The term “name space” is hereafter used as a synonym for the term “schema”).
According to the known method, data types can thereby be bequeathed from other data types. This inheritance relationship allows an instance of a bequeathed type to be used in an XML document instead of an instance of the basic type.
Based on the basic type the type code signals which type an instance is. Based on a basic type in a first name space, the inheritance structure must be analyzed over a number of name spaces during encoding and/or decoding to determine the addressable type names in a second name space. To this end an inheritance tree is established, as described in ISO/IEC 15938-1 “Multimedia Content Description Interface—Part 1: Systems”, Geneva 2002.
This assumes that all the name spaces are known and the entire inheritance tree can be established in the memory. The entire inheritance tree comprises the qualifiers of the said types of all the name spaces referenced for the instantiation of an XML description and/or XML document and their inheritance relationship. The described method is therefore very complex.